Investigation of Potential Mineral Entrapment Using Airborne Magnetic and Radiometric Data of Ado-Ekiti, Southwestern Nigeria

Abstract

In this work the mineral entrapment potentials of Ado-Ekiti were assessed using the airborne magnetic and radiometric data collected from the Nigerian Geological Survey Agency. To define structural patterns, to delineate lithological boundaries and to estimate depths to magnetic sources, the study utilizes a complete suite of magnetic data-processing techniques such as reduction-to-equator, first vertical derivative, analytic signal, tilt derivative, upward and downward continuation and 3-D Euler deconvolution. These outputs display the structural trends that are mostly NE–SW and NW–SE and are interpreted to represent the influence of the Pan-African Basement Complex, the principal fracture zones and shear belts and intrusive contacts. The geochemical differences such as variation in the composition of rocks and mineral assemblages can be seen in the maps of potassium, thorium and uranium and the ternary composites on the study area resulted from radiometric interpretation. As suggested by the spatial relationships between the felsic units, the pegmatite bodies and the alteration zones, high values for K, Th and U outline the areas affected by the hydrothermal processes. Coordinated magnetic and radiometric results give a good reinforcement in identifying the favourable targets. Magnetic lineament crossings of radiometric highs are known in a few places and are interpreted as prospective areas where the rocks are structurally controlled for concentration of minerals, and where alteration or mineralization of rocks occurs. The Euler solutions indicate depths ranging from shallow (~100 m) to deeper (>1 km) and some of these are very deep into the subsurface and could include mineralised systems.